AN IMPLICIT INTEGRAL METHOD TO SOLVE SELECTED RADIATIVE-TRANSFER PROBLEMS .2. LTE STELLAR ATMOSPHERE MODELS

The implicit integral method that we have already introduced in a prev ious paper, together with its application to the non-LTE line formatio n problem, is considered here for another paradigm problem, namely, th e self-consistent temperature correction when computing LTE stellar at mosphere models. The specific form of the source function, required by the algorithm, is obtained through a linear expansion of the Planck f unction around a trial temperature distribution. The correct solution is quickly obtained via an iterative correction procedure. The nonmatr icial structure, which is the distinctive feature of the implicit inte gral method, offers the possibility to take into account a very large number of frequency, angle, and depth discrete points, without any pen alty in terms of numerical or computational problems. Several examples are presented and discussed, to show the accuracy, robustness, and sp eed of the algorithm.